A coordinated axle torque control system interprets the amount of torque requested by the driver. The control System acts upon the torque request to accelerate or decelerate the vehicle. Typically, it is necessary to interpret accelerator pedal position as a torque request to deliver the desired drivability.
Accomplishing desired drivability is a complicated affair. For example, it is desirable for the vehicle to respond immediately as the driver tips into the pedal. In other words, there should be no dead zone in the initial pedal travel that yields zero response. Also, it is desirable to accomplish full extraction of the maximum amount of torque available form the power train when the pedal is fully depressed. In other words, there should be no untapped torque capability or dead zone at the end of pedal travel despite variability in torque capability between individual engines. These drivability characteristics should also be obtained despite variation in torque capability of an engine due to changes in ambient conditions, such as temperature and air pressure.